One hypothesis is that in response to α1PI therapy, thymopoiesis will increase, manifested by an increased axis of oscillation and increased numbers of recent thymic emigrants. In the proposed study, we will perform weekly TREC analysis which measures recent thymic emigrants and is definitive for thymopoiesis. We will test whether the changes in TREC numbers corresponds with changes in the CD4 counts axis of oscillation in HIV infected individuals receiving α1PI therapy as compared with HIV infected individuals with abnormally low active α1PI levels not on α1PI therapy, and HIV uninfected individuals with normal active α1PI levels not on α1PI therapy.